The analysis of linked birth and death records for Minnesota for the years 1967-73 has been completed and paper "Seasonal Patterns in Perinatal Mortality and Preterm Delivery" has been accepted for publication by the American Journal of Epidemiology in November or December. Of considerable interest is the finding that there is a significant increase in the probability of a preterm birth and of an early neonatal or late fetal death during July, August, and September of each year in Minnesota. This seasonality is most dramatic for causes of perinatal death related to infections in mother, fetus, or infant. An evaluation of these findings along with evidence in the literature for the past 20 years is highly suggestive that ascending infections during pregnancy may play a significant role in premature delivery and associated perinatal mortality.